The present invention relates to bearing isolators and more particularly to bearing isolators including a resilient member for providing a first force characteristic within a first range of travel and including an elastomeric member providing a second force characteristic within a second range of travel.
Existing bearing isolator assemblies seek to absorb manufacturing tolerances of associated components, pre-load bearings with axial loads to eliminate looseness and unwanted bearing noise, and control worm travel and rate of deceleration. Absorption of manufacturing tolerances of worm and bearing assemblies may be accomplished, while limiting travel of the components, by modulating a quantity of elastomer disposed within a pair of steel cups such that the elastomer compensates for part-to-part dimensional variations. In accordance with such methods, the shape of the cups and the shape of the elastomer are such that a specific force curve is generated when the assembly is compressed. Bearing pre-load is sought to be accomplished by applying an axial force to the inner race and resisting that force on the opposite side of the bearing on the outer race. Worm travel is controlled by limiting the amount of elastomer inside the two steel cups, and retention of conventional assemblies is provided through use of adhesives.
Unfortunately, such conventional bearing isolators may be limited in their ability to provide sufficient range of travel together with desirable force characteristics. Such bearing isolators may also lack the ability to be tuned so as to provide desirable force characteristics through necessary ranges of travel along the worm axis. Further, through use, some components of a bearing isolator, such as plastic components, may wear or creep, resulting in degradation of isolator function. Further still, some bearing isolator configurations may not provide for retention of isolator sub-components, in an assembled state during shipping. In the event that components of a bearing isolator may become dis-assembled during shipment, adding to costs downstream. Accordingly, it is desirable to have a bearing isolator providing tunable force characteristics over an increased range of travel, with improved durability in use and with improved reliability while being shipped and handled.